Information recording and reproducing apparatus, information recording and reproducing system, information processing apparatus and information reproducing apparatus

ABSTRACT

An information recording and reproducing apparatus  1  having a high efficiency of information transfer includes one or more recording media forming a plurality of recording surfaces, a plurality of heads respectively disposed on the recording surfaces, a first actuator for supporting the heads and moving the heads uniformly, a plurality of second actuators provided one for an associated one of the heads, the second actuators moving the heads independently relative to the first actuator, recording processing circuits for simultaneously outputting recording signals, and reproducing processing circuits simultaneously supplied with reproduced signals read out by the heads to reproduce information from the reproduced signals.

INCORPORATION BY REFERENCE

The present application claims priority from Japanese applicationJP2008-223330 filed on Sep. 1, 2008, the content of which is herebyincorporated by reference into this application.

BACKGROUND OF THE INVENTION

The present invention relates to an information recording andreproducing apparatus, an information recording and reproducing system,an information processing apparatus and an information reproducingapparatus. In particular, the present invention relates to a techniquefor positioning a head by using a multi-stage actuator.

In recent years, the magnetic disc apparatus and the optical discapparatus have been known as the information recording and reproducingapparatus. In such an information recording and reproducing apparatus, aplurality of recording surfaces in total are formed on one or moredisc-shaped recording media. A head for reading and writing informationis provided so as to be associated with each of the recording surfaces.

Taking a magnetic disc apparatus as am example, a plurality of heads aremoved uniformly by an actuator such as a voice coil motor, and arecaused to approach circular tracks), (so-called “cylinder”) which arecommon in radius position among a plurality of circular tracks formed onrecording surfaces of disc-shaped recording media.

Reference may be made to U.S. Pat. No. 7,035,972 (B2), Method andapparatus for power-efficient high-capacity scalable storage system.

SUMMARY OF THE INVENTION

Circular tracks formed on the recording surfaces have individuallydifferent distortions from their ideal tracks of circle. In theabove-described actuator, therefore, all heads cannot be positionedsimultaneously on the circular tracks of the recording surfaces. In astate in which one of the heads is positioned on a circular track,therefore, information reading and writing are conducted by this headand remaining heads are not used during that time.

Thus, in the conventional information recording and reproducingapparatus, only one head is used at a time even if heads are providedone for an associated one of a plurality of recording surfaces.

The present invention has been made in view of these circumstances, andthe present invention provides an information recording and reproducingapparatus, an information recording and reproducing system, aninformation processing apparatus and an information reproducingapparatus capable of raising the efficiency of information transfer.

An information recording and reproducing apparatus according to oneaspect of the present invention includes one or more recording mediahaving information recorded on predetermined tracks formed on each of aplurality of recording surfaces, a plurality of heads provided one for acorresponding one of the recording surfaces, the heads relatively movingin directions along the predetermined tracks, a first actuator forsupporting the heads and moving the heads uniformly, the first actuatorcausing the heads to approach the predetermined tracks, a plurality ofsecond actuators provided, one for a corresponding one of the heads, thesecond actuators moving the heads independently relative to the firstactuator, the second actuators suppressing deviations of the heads fromthe predetermined tracks, recording processing circuits forsimultaneously outputting recording signals which represent informationto be recorded on the predetermined tracks to the heads, and reproducingprocessing circuits simultaneously supplied with reproduced signals readout from the predetermined tracks by the heads, the reproducingprocessing circuits reproducing information from the reproduced signals.

In one embodiment of the present invention, the first actuator causesthe heads to approach the predetermined tracks on the basis of anaverage deviation of the heads.

In one embodiment of the present invention, a spindle motor whichrotates the recording media each formed in a disc shape around a commonrotation shaft is further included.

In one embodiment of the present invention, a plurality of circulartracks are formed around the rotation shaft on the recording surfaces ofthe recording media formed in a disc shape, and those circular tracksformed on the recording surfaces that are common in radius position areused as the predetermined tracks.

In one embodiment of the present invention, a plurality of circulartracks are formed around the rotation shaft on the recording surfaces ofthe recording media formed in a disc shape, and servo information isrecorded at a common circumferential position on the circular tracksformed on the recording surfaces.

In one embodiment of the present invention, the recording processingcircuits distribute information units which are successively input, tothe heads by a predetermined number which is less than the number ofrecording units forming each of the predetermined tracks.

In one embodiment of the present invention, the recording processingcircuits distribute information units which are associated with serialnumbers and which are input in order of the serial number, to the headsby a predetermined number which has consecutive serial numbers and whichis less than the number of recording units forming each of thepredetermined tracks.

In one embodiment of the present invention, whenever the heads read outinformation units from a predetermined number of consecutive recordingunits among the recording units forming each of the predeterminedtracks, where the predetermined number is less than the number ofrecording units forming each of the predetermined tracks, thereproducing processing circuits rearrange the information units in orderof serial numbers associated with the information units and output therearranged information units.

In one embodiment of the present invention, recording units forming thepredetermined tracks are divided into sets in which recording unitsapproached simultaneously by the heads continue by a predeterminednumber less than the number of recording units forming each of thepredetermined tracks, and a plurality of recording units belonging toeach of the sets are associated with serial numbers each representing arecording position of an information unit, in order of the serialnumber.

In this embodiment, a temporary storage unit capable of storing at least(c−1)×d+1 information units, where c is the total number of the headsand d is the predetermined number, may be further included.

In one embodiment of the present invention, information units associatedwith serial numbers are rearranged to a sequence of sets of informationunits to be recorded in recording units approached simultaneously by theheads among recording units forming the predetermined tracks, and inputfrom an external apparatus, and the recording processing circuitsdistribute the information units which are input as the sequence ofsets, to the heads.

In one embodiment of the present invention, the reproducing processingcircuits output information units successively read out from recordingunits forming each of the predetermined tracks by the heads to anexternal apparatus, and the external apparatus rearranges theinformation units in order of serial numbers associated with theinformation units.

In this mode, a temporary storage unit capable of storing at least cinformation units, where c is the total number of the heads may befurther included.

An information recording and reproducing system according to anotheraspect of the present invention includes an information recording andreproducing apparatus which includes one or more recording media havinginformation recorded on predetermined tracks formed on each of aplurality of recording surfaces, a plurality of heads provided one foran associated one of the recording surfaces, the heads relatively movingin directions along the predetermined tracks, a first actuator forsupporting the heads and moving the heads uniformly, the first actuatorcausing the heads to approach the predetermined tracks, a plurality ofsecond actuators provided one for an associated one of the heads, thesecond actuators moving the heads independently relative to the firstactuator, the second actuators suppressing deviations of the heads fromthe predetermined tracks, recording processing circuits forsimultaneously outputting recording signals which represent informationto be recorded on the predetermined tracks to the heads, and reproducingprocessing circuits simultaneously supplied with reproduced signals readout from the predetermined tracks by the heads, the reproducingprocessing circuits reproducing information from the reproduced signals,and an information processing apparatus for transmitting information tobe recorded on the recording media to the information recording andreproducing apparatus and receiving information reproduced from therecording media from the information recording and reproducingapparatus. The information processing apparatus rearranges informationunits associated with serial numbers to a sequence of sets ofinformation units to be recorded in recording units approachedsimultaneously by the heads among recording units forming thepredetermined tracks, and transmits the rearranged information units tothe information recording and reproducing apparatus. The recordingprocessing circuits in the information recording and reproducingapparatus distribute the information units which are input as thesequence of sets, to the heads.

In one embodiment of the present invention, the reproducing processingcircuits in the information processing apparatus output informationunits successively read out from the recording units forming thepredetermined tracks by the heads to the information processingapparatus, and the information processing apparatus rearranges theinformation units in order of serial numbers associated with theinformation units.

An information processing apparatus according to still another aspect ofthe present invention is provided for an information recording andreproducing apparatus. The information recording and reproducingapparatus includes one or more recording media having informationrecorded on predetermined tracks formed on each of a plurality ofrecording surfaces, a plurality of heads provided one for an associatedone of the recording surfaces, the heads relatively moving in directionsalong the predetermined tracks, a first actuator for supporting theheads and moving the heads uniformly, the first actuator causing theheads to approach the predetermined tracks, a plurality of secondactuators provided one for an associated one of the heads, the secondactuators moving the heads independently relative to the first actuator,the second actuators suppressing deviations of the heads from thepredetermined tracks, recording processing circuits for simultaneouslyoutputting recording signals which represent information to be recordedon the predetermined tracks to the heads, and reproducing processingcircuits simultaneously supplied with reproduced signals read out fromthe predetermined tracks by the heads, the reproducing processingcircuits reproducing information from the reproduced signals. Theinformation processing apparatus rearranges information units associatedwith serial numbers to a sequence of sets of information units to berecorded in recording units approached simultaneously by the heads amongrecording units forming the predetermined tracks, and transmits therearranged information units to the information recording andreproducing apparatus.

In one embodiment of the present invention, the information processingapparatus receives information units successively read out from therecording units forming the predetermined tracks by the heads, andrearranges the information units in order of serial numbers associatedwith the information units.

An information reproducing apparatus according to yet another aspect ofthe present invention includes one or more recording media havinginformation recorded on predetermined tracks formed on each of aplurality of recording surfaces, a plurality of heads provided one foran associated one of the recording surfaces, the heads relatively movingin directions along the predetermined tracks, a first actuator forsupporting the heads and moving the heads uniformly, the first actuatorcausing the heads to approach the predetermined tracks, a plurality ofsecond actuators provided one for an associated one of the heads, thesecond actuators moving the heads independently relative to the firstactuator, the second actuators suppressing deviations of the heads fromthe predetermined tracks, and reproducing processing circuitssimultaneously supplied with reproduced signals read out from thepredetermined tracks by the heads, the reproducing processing circuitsreproducing information from the reproduced signals.

According to the present invention, deviations of respective heads forrespective predetermined tracks are suppressed independently by aplurality of second actuators provided, one for an associated one of therespective heads. Therefore, information can be read and written by aplurality of heads simultaneously. As a result, the efficiency ofinformation transfer can be raised.

Other objects, features and advantages of the invention will becomeapparent from the following description of the embodiments of theinvention taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exemplary diagram showing a configuration example of aninformation recording and reproducing apparatus as an example of aninformation recording and reproducing apparatus according to the presentinvention;

FIG. 2 is an exemplary diagram for explaining a recording medium;

FIG. 3 is an exemplary exploded oblique view of a tip part of asuspension arm;

FIG. 4 is an exemplary block diagram showing a concrete functionconfiguration example of a positioning circuit;

FIG. 5 is an exemplary diagram for explaining relations betweenoperation quantities of a VCM and fine adjustment actuators and targettracks;

FIGS. 6A to 6D are exemplary diagrams for explaining a register functionin the information recording and reproducing apparatus;

FIG. 7 is an exemplary diagram for explaining an example of a commandissue method in the information recording and reproducing apparatus;

FIGS. 8A and 8B are exemplary diagrams for explaining a first example ofdata arrangement and data transfer in the information recording andreproducing apparatus;

FIGS. 9A and 9B are exemplary diagrams for explaining a second exampleof data arrangement and data transfer in the information recording andreproducing apparatus;

FIG. 10 is an exemplary diagram showing a result obtained by comparingthe present embodiment with a conventional art as regards a dataprocessing quantity and a drive power quantity per unit time; and

FIG. 11 is an exemplary diagram showing a result obtained by comparingthe present embodiment with a conventional art as regards the dataprocessing quantity and the drive power quantity per unit time.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Embodiments of the present invention will be described with reference tothe drawings.

FIG. 1 is a diagram showing a configuration example of an informationrecording and reproducing apparatus according to the present invention.In the present embodiment, an information recording and reproducingapparatus 1 is formed as a magnetic disc apparatus. The informationrecording and reproducing apparatus 1 forms an information recording andreproducing system 100 in conjunction with a host 99, and conducts datarecording and reproducing in response to a command from the host 99.

A plurality of disc-shaped recording media (magnetic disc media) 2 arehoused in a casing 10 of the information recording and reproducingapparatus 1. Faces of these recording media 2 are used as recordingsurfaces 2 a to 2 d for recording data. In the present embodiment, tworecording media 2 are housed in the casing 10 and a total of fourrecording surfaces 2 a to 2 d are formed. Note that the number ofrecording media 2 and the number of recording surfaces 2 a to 2 d arenot restricted to them. For example, one recording medium havingrecording surfaces on both sides may be provided, or a plurality ofrecording media each having a recording surface on one side may beprovided.

These recording media 2 are attached to a spindle motor (SPM) 3 providedon the bottom of the casing 10. The SPM 3 rotates the two recordingmedia 2 with a common rotation shaft.

FIG. 2 is a diagram for explaining the recording medium 2. In FIG. 2,the recording surface 2 a is illustrated as a representative one.However, other recording surfaces 2 b to 2 d are formed in the same way.A plurality of cylindrical (circumferential) tracks 21 having a rotationshaft R in the center are recorded concentrically on each of therecording surfaces 2 a to 2 d. In FIG. 2, only one track 21 is enlargedand shown. On each track 21, servo data areas 21 w arranged atpredetermined periods are formed. These servo data areas 21 w are formedin circumferential positions common to the recording surfaces 2 a to 2d. Servo data including address information and a burst signal arerecorded in these servo data areas 21 w.

Each track 21 includes a plurality of sectors (recording units) 21 sobtained by dividing the track every predetermined length along thecircumferential direction. These sectors 21 s are assigned sectornumbers which are unique serial numbers as described later (theso-called LBA (Logic Block Address). Data access from the host 99 isconducted by taking a sector 21 s as the unit.

Referring back to FIG. 1, a coarse adjustment actuator (first actuator)9 which supports a plurality of magnetic head sliders 4 a to 4 d(hereafter referred to simply as “heads 4 a to 4 d”) is provided in thecasing 10 of the information recording and reproducing apparatus 1. Thecoarse adjustment actuator 9 includes a voice coil motor (VCM) 7 and aplurality of suspension arms 6 a to 6 d which extend from the VCM 7 tothe recording media 2 in a comb teeth form. Heads 4 a to 4 d aresupported respectively at tip parts of the suspension arms 6 a to 6 d.These heads 4 a to 4 d are disposed so as to be opposed respectively tothe recording surfaces 2 a to 2 d of the recording media 2.

The VCM 7 causes uniform relative movement of the heads 4 a to 4 dsubstantially in the radius direction relative to the recording media 2by driving the suspension arms 6 a to 6 d in the revolution direction.As a result, the heads 4 a to 4 d move in a direction (scanningdirection) crossing the tracks formed on the recording surfaces 2 a to 2d (see FIG. 2). Since the heads 4 a to 4 d are arranged so as to overlapone another in the vertical direction (a direction perpendicular to therecording surfaces 2 a to 2 d), the heads 4 a to 4 d assume the samecircumferential position and radius position relative to the recordingmedia 2. Furthermore, since the recording media 2 are rotated by the SPM3, the heads 4 a to 4 d conduct relative movement in the direction alongthe circular tracks as well.

In addition, the heads 4 a to 4 d are attached to the suspension arms 6a to 6 d via fine adjustment actuators (second actuators) 5 a to 5 d,respectively. The fine adjustment actuators 5 a to 5 d are formed ofpiezo actuators, and the fine adjustment actuators 5 a to 5 d causeindependent relative movement of the heads 4 a to 4 d relative to thesuspension arms 6 a to 6 d. As a result, the heads 4 a to 4 d move in adirection (scanning direction) crossing tracks formed on the recordingsurfaces 2 a to 2 d (see FIG. 2). Note that the fine adjustmentactuators 5 a to 5 d are not restricted to the piezo actuators, but maybe, for example, electrostatic actuators or magnetic force actuators.

FIG. 3 is an exploded oblique view of the tip part of the suspension arm6 a. In FIG. 3, the suspension arm 6 a is illustrated as arepresentative one. However, other suspension arms 6 b to 6 d are alsoformed in the same way. An arm main body 62 is a structure obtained byconducting press working on a thin stainless plate, and fixed to the VCM7 at a base end side which is not illustrated (see FIG. 1). A flexure 64formed of a thin stainless plate is fixed partially to the arm main body62 by using spot welding or the like. The head 4 a is attached to a tippart of the arm main body 62 via the fine adjustment actuator 5 a. Thehead 4 a has a head element part 42 including a recording element and areproducing element on a tip side of a slider substrate 41. A first endof an FPC 66 is connected to the head element part 42 of the head 4 aand the fine adjustment actuator 5 a. A second end of the FPC 66 isconnected to a circuit for controlling them, i.e., an RW channel 14 aand an MA driver 15 a shown in FIG. 1. Operation of them will bedescribed in detail later.

In the present embodiment, a mode (the so-called slider drive type) inwhich the fine adjustment actuator 5 a lies between the suspension arm 6a and the head 4 a has been mentioned as an example. However, thepresent embodiment is not restricted to this. A fine adjustment actuatormay be built in the head 4 a as a MEMS (the so-called slider drivetype). A fine adjustment actuator may be built in a node part obtainedby dividing the arm main body 62 into two parts: a front part and a backpart (the so-called suspension drive type).

Referring back to FIG. 1, a system controller 22 exercises generalcontrol on other function blocks in the information recording andreproducing apparatus 1 directly or indirectly to implement desiredoperation. The system controller 22 reads out a control program groupfor conducting various kinds of processing from a ROM 29 into a RAM 28via a bus controller 24 and executes the control program group. The RAM28 functions as a program work area. As a result, the system controller22 executes positioning control and recording and reproducing control.In addition, the system controller 22 gives an order to an SPM driver13, drives the SPM 3 in the casing 10, and rotates the recording media2.

[Positioning Control]

Upon receiving a data access instruction issued by the host 99 via ahost interface 23, the system controller 22 interprets this data accessinstruction, calculates a target track (predetermined track) on whichthe heads 4 a to 4 d should be positioned, and moves the heads 4 a to 4d through a positioning circuit 26. Specifically, when reading data, thesystem controller 22 moves the heads 4 a to 4 d to position thereproducing element incorporated in each of the heads 4 a to 4 d in thecenter of each target track. On the other hand, when writing data, thesystem controller 22 moves the heads 4 a to 4 d so as to position therecording element incorporated in each of the heads 4 a to 4 d in thecenter of each target track. Here, it is supposed that target tracks onwhich the heads 4 a to 4 d should be positioned are tracks which areformed on the recording surfaces 2 a to 2 d of the recording media 2 andwhich have a common radius position (so-called cylinder).

The heads 4 a to 4 d read out servo data from the servo data areas 21 w(see FIG. 2) formed on the recording surfaces 2 a to 2 d by usingincorporated reproducing elements, respectively. These servo data areinput respectively to read/write channels (RW channels) 14 a to 14 d,amplified therein, and then input to the positioning circuit 26. Sincethe two recording media 2 are rotated by one SPM 3 and the servo areas21 w are formed in the common circumferential position on the recordingsurfaces 2 b to 2 d, timing for extracting servo data from reproducingsignals read out by the heads 4 a to 4 d can be made the same.

The positioning circuit 26 controls the VCM 7 through a VCM driver 17 onthe basis of these servo data, and thereby causes the heads 4 a to 4 dsupported respectively at the tip parts of the suspension arms 6 a to 6d to uniformly move and approach respective target tracks. Furthermore,the positioning circuit 26 adjusts the fine adjustment actuators 5 a to5 d respectively through MA drivers 15 a to 15 d on the basis ofrespective servo data, and thereby suppresses deviations of the heads 4a to 4 d from respective target tracks.

In this way, while the heads 4 a to 4 d are caused to approach thetarget tracks on the recording surfaces 2 a to 2 d under the control ofthe VCM 7, deviations of the heads 4 a to 4 d from the respective targettracks are suppressed under the control of the fine adjustment actuators5 a to 5 d. As a result, the heads 4 a to 4 d can be positionedsimultaneously on the target tracks on the recording surfaces 2 a to 2d, respectively. Since the stroke of the fine adjustment actuators 5 ato 5 d is smaller than the stroke of the VCM 7, the number of trackswhich can be scanned by the heads 4 a to 4 d is small. Furthermore,because of differences in stroke and load mass, power dissipated by thefine adjustment actuators 5 a to 5 d is extremely lower than thatdissipated by the VCM 7.

FIG. 4 is a block diagram showing a concrete function configurationexample of the positioning circuit 26. From the viewpoint of function,the positioning circuit 26 includes position error calculation circuits31 a to 31 d and fine adjustment controllers 33 a to 33 d provided so asto be respectively associated with the heads 4 a to 4 d, and includes anaverage calculation circuit 35 and a coarse adjustment controller 37.The position error calculation circuits 31 a to 31 d find differencesbetween target tracks specified by the system controller 22 and currentpositions of the heads 4 a to 4 d discriminated from servo data whichare input from the RW channels 14 a to 14 d, and calculates errorsignals (position error signals) which represent deviations of the heads4 a to 4 d from the target tracks.

The position error signals output from the position error calculationcircuits 31 a to 31 d are input to the fine adjustment controllers 33 ato 33 d, respectively. The fine adjustment controllers 33 a to 33 dgenerates control signals which suppress the deviations of the heads 4 ato 4 d from the target tracks, respectively and output the controlsignals to the fine adjustment actuators 5 a to 5 d via the MA drivers15 a to 15 d. Furthermore, the position error signals which are outputfrom the position error calculation circuits 31 a to 31 d are input tothe average calculation circuit 35 as well. The average calculationcircuit 35 calculates an average of the position error signals which areinput, and the coarse adjustment controller 37 generates a controlsignal which suppresses the average, and outputs the control signal tothe VCM 7 via the VCM driver 17. Calculation of the average positionerror is not restricted to the simple averaging, but, for example,weighted averaging or the like may be applied.

FIG. 5 is a diagram for explaining relations between operationquantities of the VCM 7 and the fine adjustment actuators 5 a to 5 dthus controlled and the target tracks. Its ordinate axis represents arotation angle of the recording media 2, and its abscissa axisrepresents deviation quantities of the heads 4 a to 4 d from the targettracks 1 to 4 obtained when the VCM 7 is fixed. A 0 position on theabscissa axis corresponds to a fixed position of the VCM 7, and returnpositions of the fine adjustment actuators 5 a to 5 d obtained when thefine adjustment actuators 5 a to 5 d are brought into the free state(non-drive state).

Tracks formed on the recording surfaces 2 a to 2 d do not necessarilydraw a true circle track because of position fluctuations of the headscaused when writing servo data, mechanical deformations of the recordingmedia 2, or the like, but draw a slightly different track for everyrecording surface and for every track. Tracks of the target tracks 1 to4 respectively on the recording surfaces 2 a to 2 d are shown in FIG. 5.The average calculation circuit 35 finds an average of deviationquantities of the heads 4 a to 4 d from the target tracks 1 to 4, andthe coarse adjustment controller 37 controls the VCM 7 according to theaverage. The operation quantity of the VCM 7 at this time is representedas “VCM operation quantity” in FIG. 5. The fine adjustment controllers33 a to 33 d control the fine adjustment actuators 5 a to 5 drespectively so as to compensate tracking residues generated because therespective target tracks 1 to 4 cannot be fully tracked even by the VCM7, i.e., differences between the tracks of the target tracks 1 to 4 andthe VCM operation quantities. Compensation displacements of the fineadjustment actuators 5 a to 5 d at this time are represented as “MAcompensation displacements” in FIG. 5. The compensation displacements(MA compensation displacements) of the fine adjustment actuators 5 a to5 d can be reduced as a whole by thus controlling the VCM 7 on the basisof the average of the deviation quantities of the heads 4 a to 4 d fromthe target tracks 1 to 4.

[Recording and Reproducing Control]

In the present embodiment, a circuit which forms a path from the host 99to the heads 4 a to 4 d, i.e., a circuit group including the hostinterface 23, the bus controller 24, error detection/correction circuits19 a to 19 d, modulation-demodulation circuits 18 a to 18 d, the RWchannels 14 a to 14 d, and the system controller 22 which exercisesgeneral control on these circuits functions as a recording processingcircuit and a reproducing processing circuit.

When recording data on the recording media 2 in accordance with a dataaccess instruction issued by the host 99, data sent from the host 99 aretemporarily stored in a buffer memory (temporary storage) 25 through thehost interface 23 and the bus controller 24. The data stored in thebuffer memory 25 are distributed to the error detection/correctioncircuits 19 a to 19 d through the bus controller 24. Here, the datastored in the buffer memory 25 are distributed to the errordetection/correction circuits 19 a to 19 d in accordance withpredetermined conditions every data unit (details will be describedlater).

The error detection/correction circuits 19 a to 19 d provide the inputdata with ECC data to be used for error detection and error correctionat the time of reproducing, and send resultant data to themodulation-demodulation circuits 18 a to 18 d. Themodulation-demodulation circuits 18 a to 18 d conduct predeterminedmodulation processing on the input data and send resultant data to theRW channels 14 a to 14 d. The RW channels 14 a to 14 d convert datawhich are input thereto to recording signals, and send the recordingsignals to the heads 4 a to 4 d. Thereby, the RW channels 14 a to 14 ddrive the recording elements incorporated in the heads 4 a to 4 d andform local inverted magnetic domain distribution on the target tracks onthe recording surfaces 2 a to 2 d. Thus, the RW channels 14 a to 14 drecord data sent from the host 99. The RW channels 14 a to 14 d outputthe recording signals to the heads 4 a to 4 d simultaneously and therebycause data from the heads 4 a to 4 d to be simultaneously recorded onthe target tracks on the recording surfaces 2 a to 2 d.

On the other hand, when reproducing data from the recording media 2 inaccordance with the data access instruction issued by the host 99, thedata represented as the local inverted magnetic domain distribution onthe target tracks on the recording surfaces 2 a to 2 d are read out asreproduced signals by the reproducing elements incorporated in the heads4 a to 4 d, and are simultaneously input to the RW channels 14 a to 14d, respectively. The RW channels 14 a to 14 d amplify the reproducedsignals to desired signal strength and output resultant signals to themodulation-demodulation circuits 18 a to 18 d. Themodulation-demodulation circuits 18 a to 18 d conduct demodulation,which is reverse processing of predetermined modulation processingconducted at the time of recording, and send the demodulated data to theerror detection/correction circuits 19 a to 19 d. The errordetection/correction circuits 19 a to 19 d conduct error detection anderror correction processing on the demodulated data. Data obtained as aresult are temporarily stored in the buffer memory 25 through the buscontroller 24.

The bus controller 24 stores the data sent from the errordetection/correction circuits 19 a to 19 d into the buffer memory 25while rearranging the data in a predetermined order every data unit(details will be described later). As soon as a predetermined amount ofdata are stored in the buffer memory 25 and the host interface 23 andthe host are ready, the data are sent out to the external host 99 viathe bus controller 24 and the host interface 23.

In the present embodiment, as many error detection/correction circuits19 a to 19 d and modulation-demodulation circuits 18 a to 18 d as thenumber of the RW channels 14 a to 14 d (four, a pair of a read channeland a write channel is counted as one channel) are provided. And pathsleading from the error detection/correction circuits 19 a to 19 d to theRW channels 14 a to 14 d via the modulation-demodulation circuits 18 ato 18 d are capable of operating in parallel. However, the presentembodiment is not restricted to this form, but it is possible to provideone error detection/correction circuit and one modulation-demodulationcircuit and cause them to conduct time-division operation which is ashigh in speed as the number of the RW channels 14 a to 14 d. In eithercase, the data processing quantity or data computation quantity of thecircuit per unit time becomes equal.

In the operation heretofore described, the system controller 22 monitorsthe operation situation of each function block and information retainedby each function block, controls supply of power to respective functionblocks such as the MA drivers 15 a to 15 d and the RW channels 14 a to14 d through a power supply control circuit 27 and controls the numberof channels which operate in parallel, in accordance with an explicitrequest from the host 99 or a predetermined condition decisionprocedure.

FIGS. 6A to 6D are diagrams for explaining a register function in theinformation recording and reproducing apparatus 1. FIG. 6A is a list ofregisters in the information recording and reproducing apparatus whichcan be accessed from the external. When the host 99 accesses theregister group, the host 99 specifies access objects by using fiveparallel transmission address lines, i.e., CS0-, CS1-, DA2, DA1 and DA0.In addition, the host 99 orders access operation contents such aswriting or reading, or uses a plurality of control lines (notillustrated) to specify an access data width. Connections between thehost 99 and the host interface 23, control methods of respective signallines, and a basic access method using them are based on a parallel ATAstandard in American National Standard for Information Technology—ATAttachment with Packet Interface-7 (ATA/ATAPI-7) specifications ANSIINCITS 397-2005 drawn up by the American National Standards Institute(ANSI). Since details are described in the standards in detail, theentire disclosure of which is hereby incorporated by reference hereinand detailed description will be omitted here.

FIG. 6B shows bit function assignment in a device register. A bit 4(DEV) is a device for selecting a desired one from a maximum twoinformation recording-reproducing apparatuses having a possibility ofbeing connected to an interface bus of the host 99. FIG. 6C shows bitfunction assignment in a status register and an alternative statusregister. A bit 7 (BSY) indicates by “1” that the information recordingand reproducing apparatus is conducting some processing. A bit 6 (DRDY)indicates an acceptance permission of an ordinary command by “1”. A bit5 (DF/SE) indicates some failure or the like other than errors in thedevice processing by “1.” A bit 3 (DRQ) indicates that data to betransferred between the host 99 and the information recording andreproducing apparatus exist by “1.” A bit 0 (ERR/CHK) indicates that anerror has occurred in processing of a command issued immediately before,by “1.”

FIG. 6D shows bit function assignment in a device control register. Abit 7 (HOB) specifies a function of a register capable of reading out aplurality of values (for example, readout changeover of LBA (7:0) andLBA (31:24). The bit 7 is cleared by writing into a command register orwriting a value with the bit 7 (HOB) set equal to “0” into the devicecontrol register. The bit 7 is set by writing a value with the bit 7(HOB) set equal to “1” into the device control register, and it becomespossible to read out a desired value from a register from which aplurality of values can be read out. A bit 2 (SRST) in the devicecontrol register is a bit for ordering the information recording andreproducing apparatus to reset software. By writing “1”, the informationrecording and reproducing apparatus executes the software reset. A bit 1(nIEN) in the device control register is a bit for controlling whetherto permit the information recording and reproducing apparatus to issuean interrupt request to the host. Only when the bit 1 has “0” writtentherein and the information recording and reproducing apparatus isselected, it becomes possible for the information recording andreproducing apparatus to issue an interrupt request as occasion demands.As shown in the Table, other bits are reserved bits or a “0” specifiedbit. When writing into the device control register, it is necessary toset other bits to “0” without fail.

FIG. 7 is a diagram for explaining an example of a command issue methodin the information recording and reproducing apparatus 1. As an example,the case where data retained by the host 99 is transferred to theinformation recording and reproducing apparatus 1 and recorded will nowbe described.

First, the host 99 operates the interface, and reads out the alternativestatus register (see FIG. 6C) in the information recording andreproducing apparatus 1 (S1). Until a BSY bit and a DRQ bit in theresult read out become respectively “0” and “0”, the host 99 repeatsreadout of the alternative status register and check and waits (S2). Ifthe BSY bit and the DRQ bit in the result read out become respectively“0” and “0”, then the host 99 writes a value which specifies an accessobject device into a DEV bit of the device register (see FIG. 6B), andconducts selection of the information recording and reproducingapparatus 1 (S3). Subsequently, the host 99 reads out the alternativestatus register again (S4). Until the BSY bit and the DRQ bit in theresult read out become respectively “0” and “0”, the host 99 repeatsreadout of the alternative status register and check and waits (S5). Ifthe BSY bit and the DRQ bit become respectively “0” and “0” as a resultof the readout and check, then the host 99 writes a maximum number ofchannels which are accessed simultaneously at the time of recording andreproducing into a function register (not illustrated) (S6).

In the above-described ANSI INCITS 397-2005 standards, contents to bewritten into the function register which are parameters of a WRITE DMAEXT command or the like have been reserved. In the present embodiment,however, the function of the register is redefined (expanded) and used.Since the function register has an 8-bit width, a writable value becomesan integer which is in the range of 0 to 255 in decimal number. However,a write value 0 means that the information recording and reproducingapparatus 1 dynamically determines the number of channels which areaccessed simultaneously at the time of recording and reproducing. Awrite value 255 is a value reserved for the future expansion and itcannot be specified under the existing circumstances. In the case wherethe information recording and reproducing apparatus 1 dynamicallyconducts automatic determination of the number of channels which areaccessed simultaneously at the time of recording and reproducing, theinformation recording and reproducing apparatus 1 refers to temporalissuance frequency of the access command and the data quantity subjectedto the access request per unit time. As for the specification of thenumber of channels accessed simultaneously at the time of recording andreproducing by using a write value in the range of 1 to 254, theoperation with the number of channels of the specified value is made thebasis in the same way as the case of the above-described automaticdetermination. However, the number of channels in simultaneous operationcan be reduced autonomously and temporarily with a specified valueserving as an upper limit on the basis of the operation situation of theinformation recording and reproducing apparatus 1. These operations aresupposed to be conducted in the case where simultaneous access becomestemporarily impossible because of a defect on the recording media 2 orlarge deviation of a track of a specific track from that of anothertrack between the recording media 2.

In addition, the host 99 writes the number of sectors (16 bit value) ofdata to be recorded into a sector count register group (not illustrated)(S7), writes a sector number (48 bit value) to be started in recordinginto a LBA register group (S8), and finally writes a command number 35 h(hexadecimal notation) which means the WRITE DMA EXT command into thecommand register (S9). Subsequently to the command issuance, the host 99starts sending of recording data using DMA transfer to the informationrecording and reproducing apparatus 1 (S10). Upon termination of the DMAtransfer, the host 99 reads out the status register again (S11). Thehost 99 ascertains that the BSY bit, the DRQ bit and the ERR bit are “0”(S12 and S13), and terminates the recording processing started inresponse to the WRITE DMA EXT command (S14). If the ERR bit is “1” inthis check, some error has occurred in the recording processing.Therefore, the host 99 regards the recording processing as beingterminated abnormally, and starts analysis processing of error contentsand error recovery processing (S15).

[First Example of Data Arrangement]

FIGS. 8A and 8B are diagrams for explaining a first example of dataarrangement and data transfer in the information recording andreproducing apparatus 1. FIG. 8A schematically shows data arrangement onthe recording media 2. In the present embodiment, four recordingsurfaces 2 a to 2 d are formed by the two recording media 2 andrecording and reproducing are conducted by using the four heads 4 a to 4d respectively associated with the recording surfaces 2 a to 2 d. Inother words, the maximum number of simultaneous accesses (=the number ofheads=the number of channels) is set to c=4. For brevity, alternativesectors secured on recording media in the ordinary information recordingand reproducing apparatus will not be considered.

A plurality of tracks arranged in a concentric circle form are formed oneach of the recording surfaces 2 a to 2 d of the recording media 2.Among them, a cylinder number is assigned to tracks having a commonradius position. Cylinder numbers ranging from 0 to a common maximumvalue are assigned in order from the outer circumference side of therecording surfaces 2 a to 2 d. If the cylinder number is the same, theradius position on the recording surfaces 2 a to 2 d is common. Themaximum value of the cylinder number depends upon a minimum radius, amaximum radius and a cylinder density per unit radius of recording areasof the recording surfaces 2 a to 2 d.

Each cylinder is further differentiated by the heads 4 a to 4 d(differentiated by head number 0, 1, 2 and 3) used for recording andreproducing. It is possible to uniquely specify a track to be accessedby specifying a unique track number based on a cylinder number and ahead number. Here, a value obtained by adding the head number to c timesthe cylinder number (where c=the maximum number of simultaneousaccesses=the number of heads=the number of channels: in the presentexample c=4) is regarded as the track number.

Each track is equally divided into a predetermined number of sectors(recording units) in the circumferential direction. Each data unit (forexample, 512 bytes) is recorded in a sector. In tracks 0 to 7 in anoutermost part shown in FIG. 8A, each track is divided into n/4 sectors.In the present example, sector numbers assigned to respective sectorsare not assigned in the order of number over one circumference of atrack. A predetermined number d sector numbers are assigned to each ofthe four tracks in the same cylinder. In other words, sector numbers areassigned in the number order in a set of sectors which are consecutiveby a predetermined number d and which are common in the radius positionand circumferential position. Here, sectors which are common in theradius position and circumferential position are sectors which can beaccessed simultaneously by the heads 4 a to 4 d.

Specifically, sector numbers are assigned to d sectors consecutively ona first track (for example, track: 0) beginning with a referencerotation angle position (0 degree position) of the recording media 2(rotation angle range: 0 to 1440 d/n, sectors: 0 to 3). Subsequently,sector numbers are assigned to d sectors consecutively in the samerotation angle range of another track (track: 1) in the same cylinder(sectors: 4 to 7). Thus, sector numbers are assigned in the number orderto 4 d tracks existing in the predetermined rotation angle range (0 to1440 d/n) in the same cylinder (sectors: 0 to 15). Thereafter, returningto the first track (track: 0) in the same cylinder, subsequent sectornumbers (sectors: 16 to 19) are assigned to the next rotation anglerange (1440 d/n to 2880 d/n). If sector numbers (sectors: 0 to n-1) havebeen assigned to the whole circumference of the same cylinder, thensector numbers (sectors: n to 2 n-1) are assigned successively to thenext cylinder in the same way.

The case where data units corresponding to n−16 sectors are to berecorded in a range of a sector n+16 to a sector 2 n-1 will now beconsidered. In this case, the host 99 first issues a record command tothe host interface 23 to record data. The record command is formed ofinformation such as a record start sector number and a record dataquantity of a sector unit. By the way, it is also possible to make therecord command include the number c of channels which operatesimultaneously at the time of recording and make the informationrecording and reproducing apparatus 1 control the number of channelswhich operate simultaneously in accordance with its specified value.

Subsequently, data units to be recorded are transferred from the host 99in the order of the sector number such as n+16, n+17, n+18, n+19, n+20,n+21, n+22, n+23, n+24, . . . , and stored in the buffer memory 25. Ifstorage of data units in the buffer memory 25 is continued and storageof the sector n+16 to sector n+28 is completed (in other words, thequantity of stored data units amounts to a quantity corresponding to(c−1)×d+1=13 sectors), then it is meant that data units to be recordedin head sectors among sectors to be recorded on respective tracks havebeen prepared, and data recording operation is started in accordancewith the procedure described earlier. In parallel therewith, data unitsto be recorded are transferred consecutively from the host 99 to thehost interface 23 and storage of data into the buffer memory 25 iscontinued.

FIG. 8B shows a transfer sequence of data units transferred on the hostinterface 23. The data units are stored in the buffer memory 25 in theorder of the sector number in accordance with the transfer sequence onthe host interface 23 represented as n+16, n+17, n+18, n+19, n+20, n+21,n+22, . . . . However, the bus controller 24 rearranges the sequence,and conducts operation of distributing data units to the heads 4 a to 4d by d consecutive sector numbers so as to make the head 4 a (headnumber 0) record data units of sectors n+16, n+17, n+18, n+19, . . . ,2n−16, 2n−15, 2n−14, 2n−13, make the head 4 b (head number 1) recorddata units of sectors n+20, n+21, n+22, n+23, . . . , 2n−12, 2n−11,2n−10, 2n−9, make the head 4 c (head number 2) record data units ofsectors n+24, n+25, n+26, n+27, . . . , 2n−8, 2n−7, 2n−6, 2n−5, and makethe head 4 d (head number 3) record data units of sectors n+28, n+29,n+30, n+31, . . . , 2n−4, 2n−3, 2n−2, 2n−1.

Thus, in the present example, the number of sectors over which sectornumbers are assigned consecutively on one track is set equal to d (=4)which is less than the number (n/4) of sectors forming the track.Therefore, the time required until the start of the data recordoperation can be shortened and the capacity of the buffer memory 25 canbe reduced. In other words, in the present example, data recordingoperation on the recording media 2 is started when data unitscorresponding to (c−1)×d+1 sectors are previously stored in the buffermemory 25. On the other hand, if the case where consecutive sectornumbers are assigned over one track is supposed, the data recordingoperation on the recording media 2 cannot be started unless datacorresponding to (c−1)×n/4+1 sectors are stored in the buffer memory 25.

According to the present example heretofore described, the sequence ofdata units transferred on the host interface 23 is made the same as theconventional sector number sequence. Owing to the simultaneous recordingoperation using a plurality of RW channels 14 a to 14 d, however, itbecomes possible to raise the sequential data transfer speed.Furthermore, it is possible to suppress the data unit quantity to bepreviously transferred until the data recording operation is started toa comparatively small value corresponding to (c−1)×d+1 sectors. And itis possible to suppress the capacity of the buffer memory 25 to acomparatively small value corresponding to (c−1)×d+1 sectors at aminimum. Therefore, the data recording operation is started in acomparatively short time after the host 99 issues a record command andtransfer of data to be recorded is started. As compared with theconventional information recording and reproducing apparatus in whichonly one channel operates exclusively, it becomes possible to suppressthe degradation of access latency.

The case where data units corresponding to n−16 sectors recorded in arange of the sector n+16 to the sector 2n−1 are read out in the dataarrangement shown in FIGS. 8A and 8B will now be described. In thiscase, the host 99 first issues a readout command to the host interface23 to read out data. The readout command is formed of information suchas a readout start sector number and a readout data quantity of a sectorunit. By the way, it is also possible to make the readout commandinclude the number c of channels which operate simultaneously at thetime of readout and make the information recording and reproducingapparatus 1 control the number of channels which operate simultaneouslyin accordance with its specified value in the same way as the foregoingdescription.

As the recording media 2 rotate, the reproducing elements in the heads 4a to 4 d arrive at head sectors (sectors n+16, n+20, n+24, n+28)included in sectors to be read out. Thereupon, the head 4 a (head number0) reads out data units from sectors n+16, n+17, n+18, n+19, n+32, n+33,n+34, n+35, . . . , 2n−16, 2n−15, 2n−14, 2n−13, and stores the dataunits in the buffer memory 25 in accordance with the above-describedprocessing. At the same time, the head 4 b (head number 1) reads outdata units from sectors n+20, n+21, n+22, n+23, n+36, n+37, n+38, n+39,. . . , 2n−12, 2n−11, 2n−10, 2n−9, and stores the data units in thebuffer memory 25. The head 4 c (head number 2) reads out data units fromsectors n+24, n+25, n+26, n+27, n+40, n+41, n+42, n+43, . . . , 2n−8,2n−7, 2n−6, 2n−5, and stores the data units in the buffer memory 25. Thehead 4 d (head number 3) reads out data units from sectors n+28, n+29,n+30, n+31, n+44, n+45, n+46, n+47, . . . , 2n−4, 2n−3, 2n−2, 2n−1, andstores the data units in the buffer memory 25.

At this time, the bus controller 24 conducts processing of rearrangingdata units read out from the sectors so as to transfer the data unitsread out from the sectors in the order of the sector number whentransferring the data units from the host interface 23 to the host 99later. In other words, each time each head reads out data units from dconsecutive sectors on each track (i.e., each time a total of 4 d dataunits are read out), the bus controller 24 rearranges the data units inthe order of the sector number. In the present embodiment, immediatelyafter the head 4 a (head number 0) has read out data units from thesectors n+16, n+17, n+18, transfer of them is conducted intermittently.After the head 4 a (head number 0) has read the sector n+19 thereafter,the data units n+19 to n+31 stored in the buffer memory 25 aretransferred in the cited order. In other words, in the case of thepresent embodiment, it is necessary to store data units corresponding to(c−1)×d+1=13 sectors in the buffer memory 25, and the minimum capacityof the buffer memory 25 becomes a capacity corresponding to (c−1)×d+1=13sectors.

Thus, in the present example, the number of sectors over which sectornumbers are assigned consecutively on one track is set equal to d (=4)which is less than the number (n/4) of sectors forming the track.Therefore, the time required for the data read out to be transferred canbe shortened and the capacity of the buffer memory 25 can be reduced. Inother words, in the present example, data transfer from the buffermemory 25 to the host 99 is started when data units corresponding to(c−1)×d+1 sectors are stored in the buffer memory 25. On the other hand,if the case where consecutive sector numbers are assigned over one trackis supposed, the data transfer from the buffer memory 25 to the host 99cannot be started unless data corresponding to (c−1)×n/4+1 sectors arestored in the buffer memory 25.

According to the present example heretofore described, the sequence ofdata units transferred on the host interface 23 is made the same as theconventional sector number sequence. Owing to the simultaneous recordingoperation using a plurality of RW channels 14 a to 14 d, however, itbecomes possible to raise the sequential data transfer speed.Furthermore, it is possible to suppress the capacity of the buffermemory 25 to a comparatively small value corresponding to (c−1)×d+1sectors at a minimum. Therefore, data transfer is finished in a shorttime after the readout command is issued and data readout is started. Ascompared with the conventional information recording and reproducingapparatus in which only one channel operates exclusively, it becomespossible to suppress the degradation of access latency.

[Second Example of data Arrangement]

FIGS. 9A and 9B are diagrams for explaining a second example of dataarrangement and data transfer in the information recording andreproducing apparatus 1. FIG. 8A schematically shows data arrangement onthe recording media 2. In the present example, sector numbers areassigned in the same way as the above-described first example. In theensuing description, detailed description will be omitted as to placessimilar to those in the first example.

The case where data units corresponding to n−16 sectors are to berecorded in a range of a sector n+16 to a sector 2n−1 will now beconsidered. In the present example, the host 99 rearranges data unitsassigned sector numbers in the order of the number to a sequence of setsof data units to be recorded in sectors accessed simultaneously by theheads 4 a to 4 d, and then sends the rearranged data units to the hostinterface 23. In other words, data units to be recorded are transferredfrom the host 99 in the order of n+16, n+20, n+24, n+28, n+17, n+21,n+25, n+29, n+18, . . . , and are stored in the buffer memory 25. Ifstorage of data units in the buffer memory 25 is continued and storageof the sector n+16 to the sectors n+20, n+24 and n+28 is completed (inother words, the quantity of stored data units amounts to a quantitycorresponding to c=4 sectors), then it is meant that data units to berecorded in head sectors among sectors to be recorded on respectivetracks have been prepared, and data recording operation is started inaccordance with the procedure described earlier. In parallel therewith,data units to be recorded are transferred consecutively from the host 99to the host interface 23 and storage of data into the buffer memory 25is continued.

FIG. 9B shows a transfer sequence of data units transferred on the hostinterface 23. The data units are stored in the buffer memory 25 inaccordance with the transfer sequence on the host interface 23represented as n+16, n+20, n+24, n+28, n+17, n+21, n+25, n+29, n+18,n+22, n+26, n+30, . . . . However, the bus controller 24 conductsoperation of distributing data units to the heads 4 a to 4 d so as tomake the head 4 a (head number 0) record data units of the sectors n+16,n+17, n+18, n+19, . . . , 2n−16, 2n−15, 2n−14, 2n−13, make the head 4 b(head number 1) record data units of the sectors n+20, n+21, n+22, n+23,. . . , 2n−12, 2n−11, 2n−10, 2n−9, make the head 4 c (head number 2)record data units of the sectors n+24, n+25, n+26, n+27, . . . , 2n−8,2n−7, 2n−6, 2n−5, and make the head 4 d (head number 3) record dataunits of the sectors n+28, n+29, n+30, n+31, . . . , 2n−4, 2n−3, 2n−2,2n−1.

In the present example, the total number of sectors to be recorded byone command is a multiple of both n−16 and c=4. If the total number ofsectors to be recorded is not a multiple of c, however, then the commandmay be regarded as completed after dummy data have been transferred soas to cause the total number of sectors of data transferred on the hostinterface 23 to become a minimum multiple of c exceeding the totalnumber of sectors to be recorded, or the command may be regarded ascompleted immediately after the transfer completion of datacorresponding to the total number of sectors to be recorded. Either willdo.

Thus, in the present example, the host 99 rearranges data units to asequence of sets of data units to be recorded in sectors accessedsimultaneously by the heads 4 a to 4 d, and then sends the rearrangeddata units to the host interface 23. Therefore, the time required untilthe data recording operation is started can be shortened and thecapacity of the buffer memory 25 can be reduced. In other words, in thepresent example, data recording operation on the recording media 2 isstarted when data units corresponding to c sectors are previouslystored. On the other hand, if the case where consecutive sector numbersare assigned over one track is supposed, the data recording operation onthe recording media 2 cannot be started unless data corresponding to(c−1)×n/4+1 sectors are stored in the buffer memory 25.

According to the present example heretofore described, the host 99changes the data sending sequence and the simultaneous recordingoperation using a plurality of RW channels 14 a to 14 d is conducted. Asa result, it becomes possible to raise the sequential data transferspeed. Furthermore, it is possible to suppress the data unit quantity tobe previously transferred until the data recording operation is startedto a comparatively small value corresponding to c sectors. And it ispossible to suppress the capacity of the buffer memory 25 to acomparatively small value corresponding to c sectors at a minimum.Therefore, the data recording operation is started in a comparativelyshort time after the host 99 issues a record command and transfer ofdata to be recorded is started. As compared with the conventionalinformation recording and reproducing apparatus in which only onechannel operates exclusively, it becomes possible to suppress thedegradation of access latency.

The case where data units corresponding to n−16 sectors recorded in arange of the sector n+16 to the sector 2n−1 are reproduced in the dataarrangement shown in FIGS. 9A and 9B will now be described. As therecording media 2 rotate, the reproducing elements in the heads 4 a to 4d arrive at head sectors (sectors n+16, n+20, n+24, n+28) included insectors to be read out. Thereupon, the head 4 a (head number 0) readsout data units from sectors n+16, n+17, n+18, n+19, n+32, n+33, n+34,n+35, . . . , 2n−16, 2n−15, 2n−14, 2n−13, and stores the data units inthe buffer memory 25 in accordance with the above-described processing.At the same time, the head 4 b (head number 1) reads out data units fromsectors n+20, n+21, n+22, n+23, n+36, n+37, n+38, n+39, . . . , 2n−12,2n−11, 2n−10, 2n−9, and stores the data units in the buffer memory 25.The head 4 c (head number 2) reads out data units from sectors n+24,n+25, n+26, n+27, n+40, n+41, n+42, n+43, . . . , 2n−8, 2n−7, 2n−6,2n−5, and stores the data units in the buffer memory 25. The head 4 d(head number 3) reads out data units from sectors n+28, n+29, n+30,n+31, n+44, n+45, n+46, n+47, . . . , 2n−4, 2n−3, 2n−2, 2n−1, and storesthe data units in the buffer memory 25.

At this time, whenever the heads 4 a to 4 d read out data units fromsectors on respective tracks (i.e., whenever a total of four data unitsare read out), the bus controller 24 transfers the data units from thehost interface 23 to the host 99. In the present example, immediatelyafter the head 4 a (head number 0) has read out a data unit from thesector n+16, the head 4 b (head number 1) has read out a data unit fromthe sector n+20, the head 4 c (head number 2) has read out a data unitfrom the sector n+24, and the head 4 d (head number 3) has read out adata unit from the sector n+28, the bus controller 24 transfers the dataunits from the host interface 23 to the host 99 in the order of the headnumber (i.e., in the order of n+16, n+20, n+24 and n+28). In otherwords, the data units are transferred to the host 99 in the same orderas that shown in FIG. 9B. And the host 99 rearranges the data units inthe order of the sector number.

Thus, in the present example, the host 99 rearranges data units in theorder of the sector number. Therefore, the time required for the dataread out to be transferred can be shortened and the capacity of thebuffer memory 25 can be reduced. In other words, the informationrecording and reproducing apparatus 1 does not rearrange data units inthe order of the sector number, but the host 99 rearranges data units inthe order of the sector number. Owing to the simultaneous reproducingoperation using a plurality of RW channels 14 a to 14 d, therefore, itbecomes possible to raise the sequential data transfer speed.

In the first example and the second example, writing or reading areconducted simultaneously by using all of the four heads 4 a to 4 d.However, this is not restrictive, but a part (although it is aplurality) of the four heads 4 a to 4 d may be used to conductsimultaneously writing or reading. Even in this case, it can beconsidered that configurations meeting configurations according toclaims are included in the information recording and reproducingapparatus 1. For example, when two heads among the four heads 4 a to 4 dare used, it can be considered that the information recording andreproducing apparatus 1 includes two recording surfaces, two heads andtwo second actuators and a configuration which conducts writing andreading simultaneously by using these two heads.

Finally, an approximate estimate of a power saving effect of the presentembodiment heretofore described will now be described.

FIG. 10 is a diagram showing a result obtained by comparing the presentembodiment heretofore described with a conventional art as regards dataprocessing quantity and drive power quantity per unit time. Here, theconventional art is a system obtained by striping n conventionalinformation recording and reproducing apparatuses which exclusivelyconducts processing of recording or reproducing with only one channel,by using an external controller.

The present embodiment differs from the conventional art in that thesimultaneous recording operation or simultaneous reproducing operationis implemented in one information recording and reproducing apparatusand consequently the operation speed or the number of partial functionblocks is increased to n times. Other basic specifications such as thenumber of heads and the number of recording media per informationrecording and reproducing apparatus, the recording density, physicaldimensions of the recording media and the rotation speed of therecording media are the same. For brevity, it is now supposed that thepower dissipation of semiconductors is proportional to only the productof the circuit scale (the number of gates) and the data processingquantity i.e., the computation quantity (operation frequency) per unittime and the effect of the leak current is negligibly small. In theensuing description, the circuit scale, the data processing quantity perunit time, and power dissipation of each block in the conventional artare considered as criteria of magnification.

Among various kinds of processing concerning the magnetic headpositioning, the data processing quantity per unit time required forpositioning of the fine adjustment actuators becomes n times in theconventional art, because n information recording and reproducingapparatuses are used. In the present embodiment as well, the dataprocessing quantity per unit time required for positioning of the fineadjustment actuators becomes n times, because n heads are positionedsimultaneously. On the other hand, the data processing quantity per unittime required for positioning of the VCM becomes n times in theconventional art, because n information recording and reproducingapparatuses are used. On the other hand, in the present embodiment, thedata processing quantity per unit time required for positioning of theVCM increases little and remains approximately one time, because onlyone VCM exists.

Among various kinds of processing concerning the rotation of therecording media, the data processing quantity per unit time required forthe rotation control of the SPM becomes n times in the conventional art,because one information recording and reproducing apparatus is used. Onthe other hand, in the present embodiment, the data processing quantityper unit time required for the rotation control of the SPM increaseslittle and remains approximately one time, because only one SPM exists.

Among various kinds of processing concerning the recording andreproducing signal processing, the data processing quantity per unittime in the RW channels, the modulation-demodulation circuits and theerror detection/correction circuits becomes n times in both theconventional art and the present embodiment, because n channels operatesimultaneously.

Among various kinds of processing concerning the periphery of the hostinterface, the data processing quantity per unit time required for thebuffer memory control becomes n times in both the conventional art andthe present embodiment, because the data transfer speed of a system isincreased to n times as compared with one conventional informationrecording and reproducing apparatus. The data processing quantity perunit time concerning the data rearrangement becomes n times in both theconventional art and the present embodiment. Because the externalcontroller processes a data transfer band of n times in the conventionalart, whereas the bus controller processes a data transfer band of ntimes in the present embodiment. The data processing quantity per unittime required for processing of a command issued by the host becomes ntimes in the conventional art, because n interfaces are used. On theother hand, in the present embodiment, the data processing quantity perunit time required for processing of a command issued by the hostremains approximately one time in the present embodiment, because theinterface is limited to one. The data processing quantity per unit timerequired for transfer of data reproduced or to be recorded consequentlybecomes n times in the conventional art because of one time speed and ninterfaces, whereas it becomes n times in the present embodiment as wellbecause of n times speed and one interface.

Summarizing the foregoing description, therefore, the power dissipationis prevented in the present embodiment from increasing as regards itemsof the VCM control processing/drive, SPM control processing/drive andcommand processing. As regards the power dissipation, therefore, thepresent embodiment becomes advantageous over the conventional art.Besides, the number of drives can be reduced and inevitably the numberof components included in the system can be reduced in the presentembodiment as compared with the conventional art. In the presentembodiment, therefore, it becomes possible to suppress the physicalvolume, weight and failure rate of the system. Furthermore, since thenumber of comparatively large movable parts such as the SPM and VCM isalso suppressed, a secondary effect that generation of noise andvibration caused by these operations can be suppressed is brought about.

FIG. 11 is a diagram showing a result obtained by comparing the presentembodiment with another conventional art as regards the data processingquantity and drive power quantity per unit time. Here, the conventionalart is one conventional information recording and reproducing apparatuswhich exclusively conducts processing of recording or reproducing withonly one channel.

The present embodiment differs from the conventional art in that thesimultaneous recording operation or simultaneous reproducing operationis implemented in one information recording and reproducing apparatusand consequently the operation speed or the number of partial functionblocks is increased to n times and the rotation speed of the recordingmedia is changed to 1/n times. Other points are the same as those in thecase of FIG. 10.

Among various kinds of processing concerning the magnetic headpositioning, the data processing quantity per unit time required forpositioning of the fine adjustment actuators in the present embodimentbecomes n times as compared with the conventional art, because n headsare positioned simultaneously in the present embodiment. The dataprocessing quantity per unit time required for positioning of the VCMdiffers little and remains approximately one time in both theconventional art and the present embodiment, because only one VCMexists.

Among various kinds of processing concerning the rotation of therecording media, the data processing quantity per unit time required forthe rotation control of the SPM in the present embodiment becomesapproximately 1/n times as compared with the conventional art, becausethe number of rotations of the SPM becomes 1/n in the presentembodiment. In addition, friction in the bearing part and frictionbetween the recording media and the air in the present embodiment become1/n⁴ as compared with the conventional art, because the frictions areproportional to approximately the fourth power of the rotation speed ofthe SPM in the present embodiment.

Among various kinds of processing concerning the recording andreproducing signal processing, the data processing quantity per unittime required for the analog part in the present embodiment becomesapproximately n times as compared with the conventional art, because nchannels simultaneously operate in the RW channels in the presentembodiment. On the other hand, the data processing quantity per unittime per channel in the modulation-demodulation circuit and the errordetection/correction circuit becomes proportional to the number ofrotations of the disc and becomes 1/n. In the present embodiment,however, n channels operate simultaneously. When viewed as theinformation recording and reproducing apparatus as a whole, therefore,the effect is canceled and consequently the data processing quantity perunit time per channel in the modulation-demodulation circuit and theerror detection/correction circuit becomes approximately one time.

As for the data processing quantity per unit time concerning the buffermemory control as well among various kinds of processing concerning theperiphery of the host interface, the processing quantity per channel inthe present embodiment becomes proportional to the number of rotationsof the disc and becomes 1/n. In the present embodiment, however, nchannels operate simultaneously. When viewed as the informationrecording and reproducing apparatus as a whole, therefore, the effect iscanceled and consequently the processing quantity per channel in thepresent embodiment becomes approximately one time. As for the dataprocessing quantity per unit time required for data distribution, thefunction block is not necessary in the conventional art whereas thenecessity for newly conducting processing occurs in the presentembodiment. In the present embodiment, therefore, power dissipation isincreased because of the function block. The data processing quantityper unit time required for processing of a command issued by the hostremains approximately one time in both the conventional art and thepresent embodiment, because the interface is limited to one in number.The data processing quantity per unit time required for transfer of datareproduced or to be recorded does not change in both the conventionalart and the present embodiment, and consequently it becomesapproximately one time in both the conventional art and the presentembodiment.

Summarizing the foregoing description, therefore, the data processingquantity concerning the SPM control processing in the present embodimentcan be reduced remarkably as compared with the conventional art, andpower dissipation required for the SPM drive and the SPM controlprocessing/drive can be reduced. On the other hand, in function blocksof fine adjustment actuator positioning processing/drive, analog systemrecording and reproducing signal processing and datadistribution/alignment processing, the data processing quantity per unittime or the number of simultaneously operating circuits in the presentembodiment increase as compared with the conventional art. In thepresent embodiment, power dissipation caused by these function blocksincreases as compared with the conventional art. As for logic circuitsconcerning various kinds of data processing, however, power dissipationcan be basically reduced owing to their finer circuit manufactureprocess. The ratio of their power dissipation in the whole informationrecording and reproducing apparatus can be expected to reduce in thefuture. And the fine adjustment actuators are small in movable range andthe ratio of their power dissipation in the whole information recordingand reproducing apparatus is extremely small. Therefore, it can beexpected that the present embodiment will become more advantageous inthe future as compared with the conventional art as regards the powerdissipation.

As heretofore described, the present invention makes it possible toreduce energy dissipation caused by the mechanism system such as the SPMwhich rotates the recording media and the VCM which moves the headsmounting the recording and reproducing elements, while maintaining theconsecutive data transfer rate at the time of sequential access, andmakes it possible to implement power saving of the information recordingand reproducing apparatus itself or the information recording andreproducing system using the information recording and reproducingapparatus. In other words, even when increasing the consecutive datatransfer rate at the time of sequential access to n times as comparedwith the case where only one information recording and reproducingapparatus according to the conventional art is used, only oneinformation recording and reproducing apparatus according to the presentembodiment is needed in the present embodiment. Therefore, the presentembodiment has an advantage that the access processing capability perunit power dissipation can be improved remarkably.

Even when keeping the consecutive data transfer rate at the time ofsequential access in the present embodiment equal to that in the casewhere only one information recording and reproducing apparatus accordingto the conventional art is used, the present embodiment has an advantagethat the access processing capability per unit power dissipation can beimproved remarkably supposing a decrease of energy dissipation ofsemiconductor itself owing to a finer semiconductor working process,because energy dissipation caused by the mechanism system such as theSPM and the VCM can be reduced.

In addition, in the present embodiment, the rotation of the recordingmedia is not stopped basically unlike the MAID (Massive Arrays ofInactive Disks) technique. Therefore, the spin up time of theinformation recording and reproducing apparatus is not added to theaccess latency. As a result, access performance fall and consequent fallof the system operation efficiency fall are not caused. In addition, itbecomes unnecessary to use a large-capacity buffer formed of asemiconductor memory or the like together as a measure for preventingthe access performance from falling. In addition, since a remarkableincrease of current dissipation of the information recording andreproducing apparatus caused by frequent spin up is eliminated, itbecomes unnecessary to ensure a large output capacity of the powersupply in preparation therefore. For these reasons, the presentembodiment becomes extremely advantageous in respects of the accessperformance, cost and installation size of the information recordingsystem as well. Furthermore, since the spin up and spin down of thedrive do not basically increase, a tri-pological problem between theheads and the recording media is not apt to occur. Therefore, thepresent embodiment becomes extremely advantageous in the respect of thereliability of the information recording system as well.

As heretofore described, the present embodiment is capable ofimplementing the power saving of the information recording andreproducing apparatus and improving the access processing performanceper dissipated power without hampering its access performance,especially its sequential access performance to the utmost.

Heretofore, the embodiment of the present invention has been described.However, the present invention is not limited to the above-describedembodiment, but it is a matter of course that various modifications arepossible to those skilled in the art.

For example, in the embodiment, the recording media 2 have beenexemplified as recording media. However, they are not restrictive, butstrip-shaped, cylindrical or columnar recording media may also be used.Furthermore, in the embodiment, circular tracks have been exemplified astracks formed on the recording surfaces of the recording media. However,they are not restrictive, but spiral-shaped tracks may be used. In theembodiment, the recording scheme has been the magnetic recording.However, this is not restrictive, but the thermal assisted magneticrecording or the optical recording may also be used.

In the embodiment, an information recording and reproducing apparatuscapable of conducting both data recording and data reproducing has beenused. However, the recording processing function may be omitted from theconfiguration and the apparatus may be configured as an informationreproducing apparatus.

It should be further understood by those skilled in the art thatalthough the foregoing description has been made on embodiments of theinvention, the invention is not limited thereto and various changes andmodifications may be made without departing from the spirit of theinvention and the scope of the appended claims.

The invention claimed is:
 1. An information recording and reproducingapparatus, for use with a recording medium with recorded information onpredetermined tracks formed on a plurality of recording surfaces, theinformation recording and reproducing apparatus comprising: a pluralityof heads, each head provided for an associated recording surface, thehead configured to move in a direction along a predetermined track; afirst actuator for coarse adjustment, configured to support the heads,move the heads uniformly, and cause the heads to approach theirpredetermined tracks, the first actuator including a single voice coilmotor (VCM) and a plurality of individual arms coupled to the VCM, eachindividual arm provided for an associated head and configured to move inaccordance with driving by the VCM; a plurality of second actuators forfine adjustment, each second actuator provided for an associated head,disposed between the associated head and an associated arm, adapted tosupport the associated head, configured to move the associated headindependently relative to the first actuator, and configured to moveindependently of the associated arm so as to suppress deviations of thehead from the predetermined track; a plurality of recording processingcircuits configured to simultaneously output recording signals whichrepresent information to be recorded on the predetermined tracks to theheads; a plurality of reproducing processing circuits configured to besimultaneously supplied with reproduced signals read out from thepredetermined tracks by the heads, the reproducing processing circuitsconfigured to reproduce information from the reproduced signals; and atemporary storage unit configured to store at least (c−1)×d+1information units, wherein c is the total number of the heads, and d isthe predetermined number; wherein a plurality of recording units formingthe predetermined tracks are configured to be divided into sets in whichrecording units approached simultaneously by the heads continue by apredetermined number less than the number of recording units formingeach of the predetermined tracks, and wherein a plurality of recordingunits belonging to each of the sets are configured to be associated withserial numbers each representing a recording position of an informationunit, in order of the serial number.
 2. The information recording andreproducing apparatus according to claim 1, wherein the first actuatoris configured to cause the heads to approach the predetermined tracks onthe basis of an average deviation of the heads from the predeterminedtracks.
 3. The information recording and reproducing apparatus accordingto claim 1, further comprising a spindle motor configured to rotate therecording media formed so as to each take a disc shape around a commonrotation shaft.
 4. The information recording and reproducing apparatusaccording to claim 1, wherein a plurality of circular tracks are formedaround the rotation shaft on the recording surfaces of the recordingmedia, so as to each take a disc shape, and wherein the circular tracksformed on the recording surfaces, which are common in radius position,are used as the predetermined tracks.
 5. The information recording andreproducing apparatus according to claim 1, wherein a plurality ofcircular tracks are formed around the rotation shaft on the recordingsurfaces of the recording media formed so as to each take a disc shape,and wherein servo information is recorded at a common circumferentialposition on the circular tracks formed on the recording surfaces.
 6. Theinformation recording and reproducing apparatus according to claim 1,wherein the recording processing circuits are configured to distributeinformation units, which are successively input to the heads by apredetermined number which is less than the number of recording unitsforming each of the predetermined tracks.
 7. The information recordingand reproducing apparatus according to claim 1, wherein the recordingprocessing circuits are configured to distribute information units whichare associated with serial numbers and which are input, in order of theserial number, to the heads by a predetermined number which hasconsecutive serial numbers and which is less than the number ofrecording units forming each of the predetermined tracks.
 8. Theinformation recording and reproducing apparatus according to claim 1,wherein whenever the heads read out information units from apredetermined number of consecutive recording units among the recordingunits forming the predetermined tracks, and the predetermined number isless than the number of recording units forming each of thepredetermined tracks, the reproducing processing circuits are configuredto rearrange the information units in order of serial numbers associatedwith the information units and output the rearranged information units.9. The information recording and reproducing apparatus according toclaim 1, wherein a plurality of information units associated with serialnumbers are rearranged to a sequence of sets of information units to berecorded in recording units approached simultaneously by the heads amongrecording units forming the predetermined tracks, and input from anexternal apparatus, and wherein the recording processing circuits areconfigured to distribute the information units which are input as thesequence of sets, to the heads.
 10. The information recording andreproducing apparatus according to claim 1, wherein the reproducingprocessing circuits output information units are configured tosuccessively read out from recording units forming each of thepredetermined tracks by the heads to an external apparatus, and whereinthe external apparatus is configured to rearrange the information unitsin order of serial numbers associated with the information units.
 11. Aninformation recording and reproducing system, for use with a recordingmedium with recorded information on predetermined tracks formed on aplurality of recording surfaces, the information recording andreproducing system comprising: an information recording and reproducingapparatus including: a plurality of heads, each head provided for anassociated recording surface, the head is configured to move in adirection along a predetermined track, a first actuator for coarseadjustment, configured to support the heads, move the heads uniformly,and cause the heads to approach their predetermined tracks, the firstactuator including a single voice coil motor (VCM) and a plurality ofindividual arms coupled to the VCM, each individual arm provided for anassociated head and configured to move in accordance with driving by theVCM, a plurality of second actuators for fine adjustment, each secondactuator provided for an associated head, disposed between theassociated head and an associated arm, adapted to support the associatedhead, configured to move the associated head independently relative tothe first actuator, and configured to move independently of theassociated arm so as to suppress deviations of the head from thepredetermined track; and a plurality of recording processing circuitsconfigured to simultaneously output recording signals which representinformation to be recorded on the predetermined tracks to the heads, aplurality of reproducing processing circuits configured to besimultaneously supplied with reproduced signals read out from thepredetermined tracks by the heads, the reproducing processing circuitsconfigured to reproduce information from the reproduced signals, and atemporary storage unit configured to store at least (c−1)×d+1information units, wherein c is the total number of the heads, and d isthe predetermined number; an information processing apparatus fortransmitting information to be recorded on the recording media to theinformation recording and reproducing apparatus and receivinginformation reproduced from the recording media from the informationrecording and reproducing apparatus, wherein the information processingapparatus is configured to rearrange information units associated withserial numbers to a sequence of sets of information units to be recordedin recording units approached simultaneously by the heads amongrecording units forming the predetermined tracks, and is configured totransmit the rearranged information units to the information recordingand reproducing apparatus; and wherein the recording processing circuitsin the information recording and reproducing apparatus distribute theinformation units which are input as the sequence of sets, to the heads;wherein a plurality of recording units forming the predetermined tracksare configured to be divided into sets in which recording unitsapproached simultaneously by the heads continue by a predeterminednumber less than the number of recording units forming each of thepredetermined tracks, and wherein a plurality of recording unitsbelonging to each of the sets are configured to be associated withserial numbers each representing a recording position of an informationunit, in order of the serial number.
 12. The information recording andreproducing system according to claim 11, wherein the reproducingprocessing circuits in the information processing apparatus outputinformation units are configured to successively read out from therecording units forming each of the predetermined tracks by the heads tothe information processing apparatus; and wherein the informationprocessing apparatus is configured to rearrange the information units inorder of serial numbers associated with the information units.
 13. Theinformation recording and reproducing system according to claim 11,wherein a plurality of circular tracks are formed around the rotationshaft on the recording surfaces of the recording media, so as to eachtake a disc shape, and wherein the circular tracks formed on therecording surfaces, which are common in radius position, are used as thepredetermined tracks.
 14. An information processing apparatus, providedfor an information recording and reproducing apparatus for use with oneor more recording media having information recorded on predeterminedtracks formed on each of a plurality of recording surfaces, theinformation processing apparatus comprising: wherein the informationrecording and reproducing apparatus includes: a plurality of heads, eachhead provided for an associated recording surface, the head configuredto move in a direction along a predetermined track, a first actuator forcoarse adjustment, configured to support the heads, move the headsuniformly, and cause the heads to approach their predetermined tracks,the first actuator including a single voice coil motor (VCM) and aplurality of individual arms coupled to the VCM, each individual armprovided for an associated head and configured to move in accordancewith driving by the VCM, a plurality of second actuators for fineadjustment, each second actuator provided for an associated head,disposed between the associated head and an associated arm, adapted tosupport the associated head, configured to move the associated headindependently relative to the first actuator, and configured to moveindependently of the associated arm so as to suppress deviations of thehead from the predetermined track, a plurality of recording processingcircuits configured to simultaneously output recording signals whichrepresent information to be recorded on the predetermined tracks to theheads, and reproducing processing circuits configured to besimultaneously supplied with reproduced signals read out from thepredetermined tracks by the heads, the reproducing processing circuitsconfigured to reproduce information from the reproduced signals, and atemporary storage unit configured to store at least (c−1)×d+1information units, wherein c is the total number of the heads, and d isthe predetermined number; wherein the information processing apparatusis configured to rearrange information units associated with serialnumbers to a sequence of sets of information units to be recorded inrecording units approached simultaneously by the heads among recordingunits forming the predetermined tracks, and is configured to transmitthe rearranged information units to the information recording andreproducing apparatus; wherein a plurality of recording units formingthe predetermined tracks are configured to be divided into sets in whichrecording units approached simultaneously by the heads continue by apredetermined number less than the number of recording units formingeach of the predetermined tracks, and wherein a plurality of recordingunits belonging to each of the sets are configured to be associated withserial numbers each representing a recording position of an informationunit, in order of the serial number.
 15. The information processingapparatus according to claim 14, wherein the information processingapparatus is configured to receive information units successively readout from the recording units forming each of the predetermined tracks bythe heads; and wherein the information processing apparatus isconfigured to rearrange the information units in order of serial numbersassociated with the information units.
 16. The information processingapparatus according to claim 14, wherein a plurality of circular tracksare formed around the rotation shaft on the recording surfaces of therecording media, so as to each take a disc shape, and wherein thecircular tracks formed on the recording surfaces, which are common inradius position, are used as the predetermined tracks.
 17. Aninformation reproducing apparatus, for use with one or more recordingmedia, each media having information recorded on predetermined tracksformed on each of a plurality of recording surfaces, the informationreproducing apparatus comprising: a plurality of heads, each headprovided for an associated recording surface, the head configured tomove in a direction along a predetermined track; a first actuator forcoarse adjustment, configured to support the heads, move the headsuniformly, and cause the heads to approach their predetermined tracks,the first actuator including a single voice coil motor (VCM) and aplurality of individual arms coupled to the VCM, each individual armprovided for an associated head and configured to move in accordancewith driving by the VCM; a plurality of second actuators for fineadjustment, each second actuator provided for an associated head,disposed between the associated head and an associated arm, adapted tosupport the associated head, configured to move the associated headindependently relative to the first actuator, and configured to moveindependently of the associated arm so as to suppress deviations of thehead from the predetermined track; reproducing processing circuitsconfigured to be simultaneously supplied with reproduced signals readout from the predetermined tracks by the heads, the reproducingprocessing circuits configured to reproduce information from thereproduced signals; and a temporary storage unit configured to store atleast (c−1)×d+1 information units, wherein c is the total number of theheads, and d is the predetermined number; wherein a plurality ofrecording units forming the predetermined tracks are configured to bedivided into sets in which recording units approached simultaneously bythe heads continue by a predetermined number less than the number ofrecording units forming each of the predetermined tracks, and wherein aplurality of recording units belonging to each of the sets areconfigured to be associated with serial numbers each representing arecording position of an information unit, in order of the serialnumber.
 18. The information reproducing apparatus according to claim 17,wherein a plurality of circular tracks are formed around the rotationshaft on the recording surfaces of the recording media, so as to eachtake a disc shape, and wherein the circular tracks formed on therecording surfaces, which are common in radius position, are used as thepredetermined tracks.